MIT Libraries logoDSpace@MIT

MIT
View Item 
  • DSpace@MIT Home
  • MIT Open Access Articles
  • MIT Open Access Articles
  • View Item
  • DSpace@MIT Home
  • MIT Open Access Articles
  • MIT Open Access Articles
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Mg II ABSORPTION AT 2 < z < 6 WITH MAGELLAN/FIRE. II. A LONGITUDINAL STUDY OF HI, METALS, AND IONIZATION IN GALACTIC HALOS

Author(s)
Matejek, Michael Scott; Simcoe, Robert A.; Cooksey, Kathy; Seyffert, Eduardo N.
Thumbnail
DownloadSimcoe_Mg II absorption.pdf (2.943Mb)
OPEN_ACCESS_POLICY

Open Access Policy

Creative Commons Attribution-Noncommercial-Share Alike

Terms of use
Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/
Metadata
Show full item record
Abstract
We present a detailed study of H I and metals for 110 Mg II absorption systems discovered at 1.98 < z < 5.33 in the infrared spectra of high-redshift QSOs. Using new measurements of rest-frame UV lines from optical spectra of the same targets, we compare the high-redshift sample with carefully constructed low-redshift control samples from the literature to study evolutionary trends from z = 0 → 5.33 (>12 Gyr). We observe a significant strengthening in the characteristic N(H I) for fixed Mg II equivalent width as one moves toward higher redshift. Indeed, at our sample's mean [bar over z] = 3.402, all Mg II systems are either damped Lyα absorbers (DLAs) or sub-DLAs, with 40.7% of systems exceeding the DLA threshold (compared to 16.7% at [bar over z] = 0.927). We set lower limits on the metallicity of the Mg II systems where we can measure H I; these results are consistent with the full DLA population. The classical Mg II systems (W[λ2796 over 0] = 0.3-1.0 A), which preferentially associate with sub-DLAs, are quite metal rich at ~0.1 solar. We applied quantitative classification metrics to our absorbers to compare with low-redshift populations, finding that weak systems are similar to classic Mg II absorbers at low redshift. The strong systems either have very large Mg II and Fe II velocity spreads implying non-virialized dynamics or are more quiescent DLAs. There is tentative evidence that the kinetically complex systems evolve in similar fashion to the global star formation rate. We speculate that if weaker Mg II systems represent accreting gas as suggested by recent studies of galaxy-absorber inclinations, then their high metal abundance suggests re-accretion of recently ejected material rather than first-time infall from the metal-poor intergalactic medium, even at early times.
Date issued
2013-01
URI
http://hdl.handle.net/1721.1/88550
Department
Massachusetts Institute of Technology. Department of Physics; MIT Kavli Institute for Astrophysics and Space Research
Journal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Matejek, Michael S., Robert A. Simcoe, Kathy L. Cooksey, and Eduardo N. Seyffert. “Mg II ABSORPTION AT 2 < z < 6 WITH MAGELLAN/FIRE. II. A LONGITUDINAL STUDY OF H I, METALS, AND IONIZATION IN GALACTIC HALOS.” The Astrophysical Journal 764, no. 1 (February 10, 2013): 9.
Version: Original manuscript
ISSN
0004-637X
1538-4357

Collections
  • MIT Open Access Articles

Browse

All of DSpaceCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

My Account

Login

Statistics

OA StatisticsStatistics by CountryStatistics by Department
MIT Libraries
PrivacyPermissionsAccessibilityContact us
MIT
Content created by the MIT Libraries, CC BY-NC unless otherwise noted. Notify us about copyright concerns.